Presently, little is known concerning requirements for vitamins and trace minerals in patients receiving total parenteral nutrition (TPN). Estimates of these micronutrient requirements will be made using both humans and dogs. Different formulations will be tested for their ability to maintain normal blood and urine levels in young children and adults. Depletion and repletion studies are to be conducted with the dogs; blood and urine micronutrient levels will be compared with tissue concentrations. The adequacy of the relatively new enzyme-cofactor function assays for riboflavin (erythrocyte glutathione reductase), thiamin (erythrocyte transketolase) and pyridoxine (erythrocyte GOT) as indicators of body stores will be further evaluated. Variability in the amounts of copper, zinc, manganese, chronium and selenium present in the component intravenous solutions, present as contaminants will be studied. Also to be determined is whether or not the micronutrient requirements can be met by placing the daily requirements for micronutrients in a single bottle of infusate (1000 ml) as opposed to distributing the daily requirements uniformly in the three liters of infusate usually given to adult patients. As is feasible, inferences will be made as to what effect drugs and specific disease states have on micronutrient needs.